Apple released an update for the iPhone on Thursday that brings the Wi-Fi Music Store to the device, as well as several security fixes and enhanced features. But, as expected, it also turns iPhones that were unlocked to run on cellular networks other than AT&T's into little more than emergency call boxes.

Macworld reported two iPhones in its office with SIM (subscriber identity module) hacks did not work after the update was installed. A message prompted the phone's owner to install "an unlocked and valid SIM card" before the phone could be completely activated. It's almost like the phone was in the same pre-activation limbo stage that frustrated many iPhone users waiting for activation the first weekend the device went on sale.

Gizmodo is reporting that both the original SIM cards as well as new SIM cards from AT&T won't work in iPhones that had been activated with the original SIM card, then unlocked from the network. That could present a huge problem for iPhone owners who thought they could get around the reactivation process by getting a new AT&T SIM card.